In the slasher films of the '70s, sexual promiscuity meant certain death: A teen's quick romp with a summer lover was usually rewarded with a knife in the head or some other, equally gruesome punishment. With underage sexual activity now practically a given (at least on the big screen), infidelity has become the hot, all-but-unforgivable sin. Look at what happened to poor Michael Douglas in "Fatal Attraction," the hard-partying buddies in "Very Bad Things" and the Miami-bound lovers in "Random Hearts."

In "What Lies Beneath," university genetics researcher Norman Spencer (Harrison Ford) has hell to pay for the marital failings of his past; he's literally haunted by his missteps. So is his wife, Claire, who's gracefully and sympathetically portrayed by Michelle Pfeiffer in this overdone, occasionally scary shocker directed by Robert Zemeckis ("Forrest Gump").

Working from a story suggested by DreamWorks guru Steven Spielberg, Zemeckis simultaneously pursues several genres, shuttling between supernatural spook-fest, adult-oriented thriller and old-fashioned haunted-house picture. References (both implicit and explicit) are sprinkled throughout the film to the oeuvre of the great Alfred Hitchcock.

Zemeckis explores an area that's been visited by everyone from Hitchcock to David Lynch: the dark underbelly of society. What does lie beneath the serene surface of the Spencers' domestic life, which plays out in a beautifully appointed mansion in seaside Vermont?

Norman, a genius type with a prestigious faculty position, seems an ideal husband. He's upright, responsible and attuned to the needs of his wife and her daughter, Caitlin (Katherine Towne), who's leaving for college. The model-pretty Claire is creative, loving and similarly supportive of her spouse and only child, who Norman long ago adopted.

Hints of potential dysfunction are soon dropped. Claire weeps as she peruses an old scrapbook that documents her triumphs as a Juilliard-trained classical cellist. Then there's the matter of her recent, traumatic auto accident, which she miraculously survived. And Norman appears troubled by the long shadow of his late father, a brilliant scientist whose home the couple has renovated.

"It's just us now," Norman announces as he snuggles in bed with his wife. His words virtually guarantee that the happy home will be turned upside down.

The crisis is a long time in coming, but Zemeckis makes the wait relatively interesting with false frights and a subplot about neighbor Warren Feur (James Remar of Drugstore Cowboy), who may bear murderous intent toward his wife, Mary (Miranda Otto). After a bit of snoopy surveillance (hello, Rear Window), Claire makes a public accusation in an awkward scene that goes unresolved.

Apparitions and eerie circumstances arise when Claire moves on to another investigation, this one hitting closer to home. What, she wonders, is the truth behind the disappearance of beautiful graduate student Madison Frank (supermodel Amber Valletta)? And did her perfect Norman have something to do with the tragedy?

To their credit, Zemeckis and screenwriter Clark Gregg leaven their horror thriller with several comic moments, including one in which Claire and her earthy friend, Jody (Diana Scarwid), consult a Ouija Board. Also amusing are a series of sessions with a disbelieving, fireball-dispensing psychiatrist (Joe Morton) and a very funny party encounter with neighbor Warren.

Still, the scares aren't nearly unnerving enough, nor is there much chemistry between Ford and Pfeiffer. The narrative takes sudden swerves as the filmmakers self-consciously try to fit multiple movies into one project. What lies beneath? Too much that adds up to too little.